Structure and pointers

[zorro68]

I need to store a list with chemical elements and its properties. I have programmed a class like this:

class Elementos
{
public:
	Elementos();
	~Elementos();
	int getZsymbol(char *Symbol);
        .....
private:
       enum {MaxElem=118,NameLen=16,NN=-999};
       struct ElementData
	{  
		int AtomicNumber;		
		char Symbol[3+1];		
		char SpanishName[NameLen+1];
		char EnglishName[NameLen+1];
		char GermanName[NameLen+1];
             .....
       }Propiedades[MaxElem],*p;
}

class Elementos
{
public:
	Elementos();
	~Elementos();
	int getZsymbol(char *Symbol);
        .....
private:
       enum {MaxElem=118,NameLen=16,NN=-999};
       struct ElementData
	{  
		int AtomicNumber;		
		char Symbol[3+1];		
		char SpanishName[NameLen+1];
		char EnglishName[NameLen+1];
		char GermanName[NameLen+1];
             .....
       }Propiedades[MaxElem],*p;
}

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And in cpp file:

#include "elementos.h"
 
Elementos::Elementos()
{
	ElementData Propiedades[MaxElem] =
	{
	       {   1, "H" , "Hidrógeno"	, "Hydrogen"     , "Wasserstoff"  }, 
		{   2, "He", "Helio"		, "Helium"       , "Helium"}
               ...
        };
       p=&Propiedades[0];
}
 
int Elementos::getZsymbol(char *Symbol)
{
	ElementData *q;
	q=p;
	string c = string(Symbol);
	for (int i=0;i<MaxElem;i++){
		string s = string(q->Symbol);
		if (c==s) return q->AtomicNumber;
		q++;
	}
	return 0;
}

#include "elementos.h"

Elementos::Elementos()
{
	ElementData Propiedades[MaxElem] =
	{
	       {   1, "H" , "Hidrógeno"	, "Hydrogen"     , "Wasserstoff"  }, 
		{   2, "He", "Helio"		, "Helium"       , "Helium"}
               ...
        };
       p=&Propiedades[0];
}

int Elementos::getZsymbol(char *Symbol)
{
	ElementData *q;
	q=p;
	string c = string(Symbol);
	for (int i=0;i<MaxElem;i++){
		string s = string(q->Symbol);
		if (c==s) return q->AtomicNumber;
		q++;
	}
	return 0;
}

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When i compile and use in debug mode works fine, but in release mode don't work.

I think that p=&Propiedades[0]; point to the first element of the Propiedades, but in getZsymbol function this pointer takes a bad value. Someone knows how can I correct this to work fine (debug and release).

Thanks

[jacek]

ElementData Propiedades[MaxElem] =
{
{ 1, "H" , "Hidrógeno" , "Hydrogen" , "Wasserstoff" },
{ 2, "He", "Helio" , "Helium" , "Helium"}
...
};

You define a new Propiedades variable here, so not only you don't initialize Elementos::Propiedades, but also you assign an address of a temporary object to p.

Do you reall want to store a copy of that table in every Elementos instance? I would define Propiedades as static.

[zorro68]

You define a new Propiedades variable here, so not only you don't initialize Elementos::Propiedades, but also you assign an address of a temporary object to p.

I have proved this:

....
}*Propiedades[MaxElem],*p;

....
}*Propiedades[MaxElem],*p;

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Propiedades[MaxElem]=new ElementData;
Propiedades[MaxElem] =
	{
		{   1, "H" , "Hidrógeno"	, "Hydrogen"     , "Wasserstoff"}, 
		{   2, "He", "Helio"		, "Helium"       , "Helium"}
    ....

Propiedades[MaxElem]=new ElementData;
Propiedades[MaxElem] =
	{
		{   1, "H" , "Hidrógeno"	, "Hydrogen"     , "Wasserstoff"}, 
		{   2, "He", "Helio"		, "Helium"       , "Helium"}
    ....

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and i get a lot of syntax errors and i don't know why. Or this:

Propiedades[0]={   1, "H" , "Hidrógeno"	, "Hydrogen"     , "Wasserstoff"};
      Propiedades[1]={   2, "He", "Helio"		, "Helium"       , "Helium"};

Propiedades[0]={   1, "H" , "Hidrógeno"	, "Hydrogen"     , "Wasserstoff"};
      Propiedades[1]={   2, "He", "Helio"		, "Helium"       , "Helium"};

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I get the same error.

Do you reall want to store a copy of that table in every Elementos instance?

No, but i don't know how?

I would define Propiedades as static.

How?

[zorro68]

I used an static variable Propiedades out of the class definition and works fine.

Thanks very much.